Message History 
Among other things, the Kernel user menu contains a display of the log files that are backed up when the database crashes, as well as the kernel message history.
Normally, at least the kernel log knldiag, the database trace log knltrace, and the memory dump rtedump are backed up if the database crashes. These files are in a subdirectory of the directory diaghistory, where they can be used for diagnoses.
Procedure
Open the Database Assistant (transaction DB50) or the liveCache Assistant (transaction LC10). Choose 
Problem Analysis 
Messages Kernel History 
.
or
Open the DBA Cockpit (transaction DBACOCKPIT) and choose Diagnosis Kernel Messages History .
Result
The existing subdirectories of the diaghistory directory are displayed, sorted according to the time your backup was performed.
The available kernel message history (KnlMsg_<time_stamp> files) is displayed. You can open and analyze any of the log files.